Thanks for your query. It is quite rare to develop such mood swings at this age. Neverthless, the possibilities include cyclothymia
(associated with mild mood swings), menstrual dysphoric disorder (if you are a female) or it could be just a transient normal phenomenon in response to some recent life stress
. Hence, i would suggest you to undergo a thorough psychiatric evaluation to rule out the above conditions and start medication if appropriate. Hope you found the information useful.
Dr Sundar G